The present invention relates in general to a method of producing pasta on an industrial scale.
The invention relates in particular to a method for the continuous extrusion through a die of a dough of semolina, water and possibly other ingredients, suitable for producing corresponding pasta products.
It is well known that, for extrusion through a die, the preselected dough must be compressed to fairly high pressures which, for the production of spaghetti and similar elongate types of pasta, for example, may reach 70-80 kg/cm.sup.2.
It is also known that so-called screw feeders have been used universally up to now in order, on the one hand, to supply a die continuously with a dough which has been compressed to these values (extrusion pressures) and, on the other hand, to ensure acceptable productivity from an industrial point of view.
Essentially, a screw feeder comprises an internally-grooved cylinder in which a worm screw rotates to knead and transport the dough towards the die.
As it advances and is compressed in the screw feeder, the dough is subjected to considerable mechanical stress and at the same time is heated appreciably because of the resilient, viscous nature of the dough, the large amount of friction with the internally-grooved wall of the cylinder and the lesser, but still considerable, amount of friction with the screw.
As a result, the structure of the dough is inevitably degraded, resulting in a recognised and equally inevitable reduction in the organoleptic quality of the pasta products produced therefrom.